a gross, stupid, or careless mistake: That's your second blunder this morning.
verb (used without object)
2.
to move or act blindly, stupidly, or without direction or steady guidance: Without my glasses I blundered into the wrong room.
3.
to make a gross or stupid mistake, especially through carelessness or mental confusion: Just pray that he doesn't blunder again and get the names wrong.
verb (used with object)
4.
to bungle; botch: Several of the accounts were blundered by that new assistant.
5.
to utter thoughtlessly; blurt out: He blundered his surprise at their winning the award.
mid-14c., "to stumble around blindly," from O.N. blundra "shut one's eyes," from PIE base *bhlendh- (see blind). Meaning "make a stupid mistake" is first recorded 1711.